1. Field of the Invention
An invention disclosed in the present specification relates to a transistor that is a semiconductor element (for example, a thin film transistor), and a display device using the same or the like. Further, the invention relates to manufacture of the transistor.
2. Description of the Related Art
In a case of manufacturing a thin film transistor, a contact hole is formed into a predetermined shape by performing dry etching with respect to an insulating film to connect a semiconductor film or a conductive film covered with the insulating film such as an interlayer insulating film or a gate insulating film; and a wiring or an electrode (for example, refer to 34 paragraph in Japanese Patent Application Laid-Open No. H10-189481).
Dry etching is not a method where acidic or alkaline liquid is used but a method where gas is used for etching. By dry etching, a pattern having almost the same size as a mask such as a resist mask can be obtained. This etching is referred to as an anisotropic etching and suitable for micro-fabrication.